Pub Date : 2023-09-08DOI: 10.1590/1517-7076-rmat-2023-0151
Zhenlong Mo
Graphene oxide (GO) has attracted more and more attention in asphalt pavement due to its excellent performance. However, most current research is limited to GO modified base asphalt, and the modification effect is insignificant. In this paper, GO / SBS-modified asphalt was prepared by high-speed shearing. The effects of GO on the physical properties, storage stability, low-temperature performance, and aging resistance of SBS-modified asphalt were studied. A low-temperature beam bending test analyzed the low-temperature performance of GO / SBS composite modified asphalt mixture before and after aging. The results show that adding GO improves SBS-modified asphalt’s high-temperature performance, aging resistance, and storage stability. When the con - tent of GO is 0.75%, the physical properties of modified asphalt are the best. The low-temperature rheological properties of modified asphalt with GO before aging are slightly lower than those of SBS-modified asphalt. However, adding GO improves the low-temperature rheological properties of GO/SBS modified asphalt after aging. GO-modified asphalt slightly improves the low-temperature toughness of the mixture under non-aging and short-term aging. However, it still makes the mixture maintain good low-temperature performance under long-term aging. GO / SBS modified asphalt mixture has excellent low-temperature crack resistance before and after aging, and GO / SBS composite modified asphalt can effectively alleviate the damaging effect of aging on the low-temperature crack resistance of asphalt mixture and prolong the service life of the pavement.
{"title":"Study on the performance and aging low temperature performance of GO / SBS modified asphalt","authors":"Zhenlong Mo","doi":"10.1590/1517-7076-rmat-2023-0151","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0151","url":null,"abstract":"Graphene oxide (GO) has attracted more and more attention in asphalt pavement due to its excellent performance. However, most current research is limited to GO modified base asphalt, and the modification effect is insignificant. In this paper, GO / SBS-modified asphalt was prepared by high-speed shearing. The effects of GO on the physical properties, storage stability, low-temperature performance, and aging resistance of SBS-modified asphalt were studied. A low-temperature beam bending test analyzed the low-temperature performance of GO / SBS composite modified asphalt mixture before and after aging. The results show that adding GO improves SBS-modified asphalt’s high-temperature performance, aging resistance, and storage stability. When the con - tent of GO is 0.75%, the physical properties of modified asphalt are the best. The low-temperature rheological properties of modified asphalt with GO before aging are slightly lower than those of SBS-modified asphalt. However, adding GO improves the low-temperature rheological properties of GO/SBS modified asphalt after aging. GO-modified asphalt slightly improves the low-temperature toughness of the mixture under non-aging and short-term aging. However, it still makes the mixture maintain good low-temperature performance under long-term aging. GO / SBS modified asphalt mixture has excellent low-temperature crack resistance before and after aging, and GO / SBS composite modified asphalt can effectively alleviate the damaging effect of aging on the low-temperature crack resistance of asphalt mixture and prolong the service life of the pavement.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88142972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the feasibility of low-grade hard asphalt in high-temperature regions. We conducted an analysis of the high-temperature rheological properties of asphalt before and after short-term and long-term aging using the dynamic shear rheological (DSR) test and multi-stress creep recovery (MSCR) test. Additionally, the road performance of the asphalt mixture was studied by rutting test and low temperature beam bending test. The results indicate that the 30# asphalt demonstrates superior anti-rutting performance compared to the 50# asphalt. Furthermore, the rutting factor and fatigue factor of the 30# asphalt during aging are significantly higher than those of the 50# asphalt. With increasing temperature, stress level, and stress action time, the strain of the asphalt gradually increases. The unrecoverable creep compliance of the 50# asphalt exceeds that of the 30#. Although the high-temperature performance of the 30# asphalt mixture outperforms that of the 50# asphalt mixture, it exhibits lower flexural tensile strength and deformation ability at low temperatures compared to the 50# asphalt mixture. Overall, low-grade asphalt demonstrates relatively stable stress variations and exhibits good high-temperature stability.
{"title":"Rheological properties and engineering application of low-grade asphalt mixture","authors":"Lianguo Song, Pengcheng Tu, Xiao-lu Xie, Jingjing Fan, Lulu Hou, Jie Gao","doi":"10.1590/1517-7076-rmat-2023-0208","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0208","url":null,"abstract":"This study investigates the feasibility of low-grade hard asphalt in high-temperature regions. We conducted an analysis of the high-temperature rheological properties of asphalt before and after short-term and long-term aging using the dynamic shear rheological (DSR) test and multi-stress creep recovery (MSCR) test. Additionally, the road performance of the asphalt mixture was studied by rutting test and low temperature beam bending test. The results indicate that the 30# asphalt demonstrates superior anti-rutting performance compared to the 50# asphalt. Furthermore, the rutting factor and fatigue factor of the 30# asphalt during aging are significantly higher than those of the 50# asphalt. With increasing temperature, stress level, and stress action time, the strain of the asphalt gradually increases. The unrecoverable creep compliance of the 50# asphalt exceeds that of the 30#. Although the high-temperature performance of the 30# asphalt mixture outperforms that of the 50# asphalt mixture, it exhibits lower flexural tensile strength and deformation ability at low temperatures compared to the 50# asphalt mixture. Overall, low-grade asphalt demonstrates relatively stable stress variations and exhibits good high-temperature stability.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88021418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1590/1517-7076-rmat-2023-0182
Ravisankar Venugopal, N. Muthusamy, Balasundaram Natarajan, Venkatesan Govindan
To meet the present needs of concrete consumption, it is the need of the hour to discover different alterna - tives and unique techniques. By Incorporating the latest trends, Polymer Concrete (PC) and Fibre-Reinforced Concrete (FRC) are being used to improve the strength of concrete. It is proposed to produce M30 grade Fibre Reinforced Polymer Concrete (FRPC) with the help of Polyester Resins (PR), Polypropylene Fibres (PF) and Recycled Waste Plastics (RWPA). FRPC is a combination of three different variables of different replacement percentages, which requires extensive and detailed experimentation to optimize each variable used in this investigation. In this study (research), optimization was done by keeping the two variables constant. To reduce the number of experiments, optimization of ingredients was done by statistical modelling technique of Central Composite Design (CCD). In conclusion, the optimal input parameters for achieving a 28-day CS are determined to be 12.05% PR, 2.19% PF, and 30% RWPA. These findings are based on the analysis of experimental results, statistical modelling, and the CCD approach, demonstrating the successful optimization and correlation between the input parameters and the desired CS output.
{"title":"Statistical optimization of fibre reinforced polymer concrete made with recycled plastic aggregates by central composite design","authors":"Ravisankar Venugopal, N. Muthusamy, Balasundaram Natarajan, Venkatesan Govindan","doi":"10.1590/1517-7076-rmat-2023-0182","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0182","url":null,"abstract":"To meet the present needs of concrete consumption, it is the need of the hour to discover different alterna - tives and unique techniques. By Incorporating the latest trends, Polymer Concrete (PC) and Fibre-Reinforced Concrete (FRC) are being used to improve the strength of concrete. It is proposed to produce M30 grade Fibre Reinforced Polymer Concrete (FRPC) with the help of Polyester Resins (PR), Polypropylene Fibres (PF) and Recycled Waste Plastics (RWPA). FRPC is a combination of three different variables of different replacement percentages, which requires extensive and detailed experimentation to optimize each variable used in this investigation. In this study (research), optimization was done by keeping the two variables constant. To reduce the number of experiments, optimization of ingredients was done by statistical modelling technique of Central Composite Design (CCD). In conclusion, the optimal input parameters for achieving a 28-day CS are determined to be 12.05% PR, 2.19% PF, and 30% RWPA. These findings are based on the analysis of experimental results, statistical modelling, and the CCD approach, demonstrating the successful optimization and correlation between the input parameters and the desired CS output.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73344692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1590/1517-7076-rmat-2023-0176
Ala’eddin A. Saif, Yen Chin Teh, Prabakaran Poopalan
Ba 1-x Gd x TiO 3 thin films have been fabricated at different Gd 3+ ionic concentrations, film thicknesses, and anneal - ing temperatures using the sol-gel method. The refractive index of the Ba 1-x Gd x TiO 3 films on a silicon substrate is characterized using Spectroscopic Ellipsometry (SE), where the ellipsometry angles Ψ and Δ are fitted very well with the Cauchy dispersion model. The results show that the refractive index at 632.8 nm decreases from 2.18 to 1.892 with the increase of the Gd 3+ ratio, while it increases with film thickness and annealing tempera - ture. This trend for refractive index variation is explained based on interatomic spacing and density densification of the films. Using Wemple–Di Domenico (WDD) model shows that the dispersion energy increases with film thickness and annealing temperature and decreases with Gd 3+ doping. The relatively high refractive index of the samples supports the possibility of using Ba 1-x Gd x TiO 3 thin films as AR coating for solar cells.
{"title":"A study on the refractive index of sol-gel Ba1-xGdxTiO3 thin films using spectroscopic ellipsometry","authors":"Ala’eddin A. Saif, Yen Chin Teh, Prabakaran Poopalan","doi":"10.1590/1517-7076-rmat-2023-0176","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0176","url":null,"abstract":"Ba 1-x Gd x TiO 3 thin films have been fabricated at different Gd 3+ ionic concentrations, film thicknesses, and anneal - ing temperatures using the sol-gel method. The refractive index of the Ba 1-x Gd x TiO 3 films on a silicon substrate is characterized using Spectroscopic Ellipsometry (SE), where the ellipsometry angles Ψ and Δ are fitted very well with the Cauchy dispersion model. The results show that the refractive index at 632.8 nm decreases from 2.18 to 1.892 with the increase of the Gd 3+ ratio, while it increases with film thickness and annealing tempera - ture. This trend for refractive index variation is explained based on interatomic spacing and density densification of the films. Using Wemple–Di Domenico (WDD) model shows that the dispersion energy increases with film thickness and annealing temperature and decreases with Gd 3+ doping. The relatively high refractive index of the samples supports the possibility of using Ba 1-x Gd x TiO 3 thin films as AR coating for solar cells.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85483725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
River sand is becoming increasingly scarce. As a result, an alternative material is required to replace river sand in order to save river sand. In the construction of quality concrete, artificial aggregate is now frequently employed as a substitute for river sand. Coconut fibre ash (CFA) aggregate obtained from Coconut fibre is prev - alent in India. Partially replacing river sand (fine aggregate) with presaturated CFA aggregate for self curing purpose is presented in the paper. Fine aggregates were replaced by CFA aggregate by 5%, 10%, 15%, 20% and 25% by volume. The workability and strength characteristics of the concrete are studied. Internal curing is the solution to today's water scarcity's insufficient curing. During compared to other mixtures, test results show that the concrete mix with 20% CFA aggregate produced better results when self curing.
{"title":"Influence of presaturated coconut fibre ash pellets in concrete","authors":"Gopi Rajamanickam, Saravanakumar Ramasamy, Elango Krishnan Soundararajan, Kathiresan Karuppanan, Chandrasekar Arumugam","doi":"10.1590/1517-7076-rmat-2023-0190","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0190","url":null,"abstract":"River sand is becoming increasingly scarce. As a result, an alternative material is required to replace river sand in order to save river sand. In the construction of quality concrete, artificial aggregate is now frequently employed as a substitute for river sand. Coconut fibre ash (CFA) aggregate obtained from Coconut fibre is prev - alent in India. Partially replacing river sand (fine aggregate) with presaturated CFA aggregate for self curing purpose is presented in the paper. Fine aggregates were replaced by CFA aggregate by 5%, 10%, 15%, 20% and 25% by volume. The workability and strength characteristics of the concrete are studied. Internal curing is the solution to today's water scarcity's insufficient curing. During compared to other mixtures, test results show that the concrete mix with 20% CFA aggregate produced better results when self curing.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"23 2 PT. 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82926453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1590/1517-7076-rmat-2023-0214
Ce Sun, Xiaoqing Li, Fanghui Guo, Junru Li, Lianjun Cheng, P. Zhang
By performing tensile tests in the temperature range of 800°C to 1200°C, the thermoplastic behavior of microal-loyed and unmicroalloyed new martensitic low-density steels were investigated, and the mechanism of the effect of Nb and V microalloying on the thermoplasticity was revealed. The results showed that both microalloyed and unmicroalloyed steels have good thermoplasticity and the plasticity increased with increasing deformation temperature. The microalloyed steels above 1000°C could have their high-temperature plasticity significantly enhanced by Nb, V microalloying, while the microalloyed steels at or below 1000°C could have their plasticity reduced. When the deformation temperature exceeds 1000°C, complete recrystallization occurs in both microal-loyed and unmicroalloyed steels. The Nb, V microalloys were able to refine the recrystallized grains, which could obtain a stronger resistance to crack expansion and give the microalloyed steels better high-temperature plasticity. When the deformation temperature at or below 1000°C, the unmicroalloyed steel exhibited significant recrystallization. The presence of numerous small-sized NbC precipitation phases, abundant in the microal-loyed steel, hindered the recrystallization. This made dynamic recrystallization of microalloyed steels almost non-existent when deformation occurred at lower temperatures, which lead to lower plasticity compared to the unmicroalloyed steel.
{"title":"Effects of Nb and V microalloying on the thermoplasticity of new martensitic low-density steels","authors":"Ce Sun, Xiaoqing Li, Fanghui Guo, Junru Li, Lianjun Cheng, P. Zhang","doi":"10.1590/1517-7076-rmat-2023-0214","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0214","url":null,"abstract":"By performing tensile tests in the temperature range of 800°C to 1200°C, the thermoplastic behavior of microal-loyed and unmicroalloyed new martensitic low-density steels were investigated, and the mechanism of the effect of Nb and V microalloying on the thermoplasticity was revealed. The results showed that both microalloyed and unmicroalloyed steels have good thermoplasticity and the plasticity increased with increasing deformation temperature. The microalloyed steels above 1000°C could have their high-temperature plasticity significantly enhanced by Nb, V microalloying, while the microalloyed steels at or below 1000°C could have their plasticity reduced. When the deformation temperature exceeds 1000°C, complete recrystallization occurs in both microal-loyed and unmicroalloyed steels. The Nb, V microalloys were able to refine the recrystallized grains, which could obtain a stronger resistance to crack expansion and give the microalloyed steels better high-temperature plasticity. When the deformation temperature at or below 1000°C, the unmicroalloyed steel exhibited significant recrystallization. The presence of numerous small-sized NbC precipitation phases, abundant in the microal-loyed steel, hindered the recrystallization. This made dynamic recrystallization of microalloyed steels almost non-existent when deformation occurred at lower temperatures, which lead to lower plasticity compared to the unmicroalloyed steel.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"749 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76857040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1590/1517-7076-rmat-2023-0106
Augusto Prata Sigeiro, R. Marcomini
RESUMO No presente estudo, lotes de placas de zircônia estabilizada com 8% mol de ítrio (TZ8Y) foram fabricados pela técnica de colagem de fita, variando entre eles a composição da suspensão, como o volume de sólidos e os teores de ligantes, de plastificante do tipo I e de plastificante do tipo II com o intuito de verificar a influência destes parâmetros e do comportamento tixotrópico da suspensão sobre o empenamento do produto final. Após sinterizadas, a topografia das placas foi mapeada por meio de um relógio comparador, tomando medidas sobre a superficia das placas em um sistema de coordenadas, e, a partir desse sistema, foi definido um índice numérico que quantifica a planicidade das amostras. A influência foi investigada através de uma análise estatística bivariada, relacionando o índice de planicidade com cada um dos parâmetros alvo. A análise apresentou uma correlação negativa forte e significativa pelo teste de Spearman (⍴ ≅ 0,95 e valor-p < 10–3) entre o teor de plastificante do tipo I e a planicidade das placas produzidas, porém para os outros parâmetros analisados a correlação não pôde ser considerada estatisticamente significativa. Além disso, os resultados mostraram também que a utilização de um pós processamento nas fitas à verde, como uma laminação, melhorou substancialmente a planicidade das placas após a sinterização.
{"title":"Análise estatística da influência dos parâmetros de processamento na planicidade de placas de zircônia estabilizada com 8%mol de ítrio obtidas por colagem de fita","authors":"Augusto Prata Sigeiro, R. Marcomini","doi":"10.1590/1517-7076-rmat-2023-0106","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0106","url":null,"abstract":"RESUMO No presente estudo, lotes de placas de zircônia estabilizada com 8% mol de ítrio (TZ8Y) foram fabricados pela técnica de colagem de fita, variando entre eles a composição da suspensão, como o volume de sólidos e os teores de ligantes, de plastificante do tipo I e de plastificante do tipo II com o intuito de verificar a influência destes parâmetros e do comportamento tixotrópico da suspensão sobre o empenamento do produto final. Após sinterizadas, a topografia das placas foi mapeada por meio de um relógio comparador, tomando medidas sobre a superficia das placas em um sistema de coordenadas, e, a partir desse sistema, foi definido um índice numérico que quantifica a planicidade das amostras. A influência foi investigada através de uma análise estatística bivariada, relacionando o índice de planicidade com cada um dos parâmetros alvo. A análise apresentou uma correlação negativa forte e significativa pelo teste de Spearman (⍴ ≅ 0,95 e valor-p < 10–3) entre o teor de plastificante do tipo I e a planicidade das placas produzidas, porém para os outros parâmetros analisados a correlação não pôde ser considerada estatisticamente significativa. Além disso, os resultados mostraram também que a utilização de um pós processamento nas fitas à verde, como uma laminação, melhorou substancialmente a planicidade das placas após a sinterização.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83965597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1590/1517-7076-rmat-2023-0085
Thaís Ramos Capai Jardim, M. Câmara, F. C. Magalhães, Anderson Júnior dos Santos
RESUMO O atrito nas interfaces ferramenta/cavaco e ferramenta/peça é complexo dificultando a determinação do coeficiente de atrito nos processos de usinagem. Assim, vários ensaios tribológicos foram desenvolvidos para simular as condições de corte e determinar o coeficiente de atrito. Este trabalho apresentou análise comparativa do coeficiente de atrito entre o aço ABNT 1045 e WC-10Co revestido com AlCrN por meio de dois métodos: ensaio de torneamento e ensaio de compressão de anel à quente. O ensaio de torneamento foi realizado com corte oblíquo nas velocidades de corte 150 e 220 m/min. A aquisição dos sinais das componentes de força da usinagem por meio de um dinamômetro. O ensaio de compressão de anel foi realizado nas temperaturas de 200 e 400 °C. Os coeficientes de atrito foram obtidos por meio de modelos matemáticos. A análise estatística do coeficiente de atrito apontou equivalência do coeficiente de atrito no ensaio de torneamento na velocidade de corte 150 m/min com o ensaio de compressão de anel à quente 200 °C. Assim como no ensaio de torneamento na velocidade de corte 220 m/min com o ensaio de compressão de anel à quente 400 °C. A análise macrográfica do anel após a deformação no ensaio de compressão de anel observou a influência da temperatura de ensaio no deslocamento do raio neutro. A análise superficial dos anéis e das matrizes do ensaio de compressão foi realizada por meio de microscopia óptica (MO) e rugosidade Ra, onde observou-se o aumento da rugosidade após o ensaio e a presença de desgaste abrasivo.
{"title":"Avaliação da aplicabilidade do ensaio de compressão de anel à quente para determinar o coeficiente de atrito no ensaio de torneamento do aço ABNT 1045 por meio de análise estatística","authors":"Thaís Ramos Capai Jardim, M. Câmara, F. C. Magalhães, Anderson Júnior dos Santos","doi":"10.1590/1517-7076-rmat-2023-0085","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0085","url":null,"abstract":"RESUMO O atrito nas interfaces ferramenta/cavaco e ferramenta/peça é complexo dificultando a determinação do coeficiente de atrito nos processos de usinagem. Assim, vários ensaios tribológicos foram desenvolvidos para simular as condições de corte e determinar o coeficiente de atrito. Este trabalho apresentou análise comparativa do coeficiente de atrito entre o aço ABNT 1045 e WC-10Co revestido com AlCrN por meio de dois métodos: ensaio de torneamento e ensaio de compressão de anel à quente. O ensaio de torneamento foi realizado com corte oblíquo nas velocidades de corte 150 e 220 m/min. A aquisição dos sinais das componentes de força da usinagem por meio de um dinamômetro. O ensaio de compressão de anel foi realizado nas temperaturas de 200 e 400 °C. Os coeficientes de atrito foram obtidos por meio de modelos matemáticos. A análise estatística do coeficiente de atrito apontou equivalência do coeficiente de atrito no ensaio de torneamento na velocidade de corte 150 m/min com o ensaio de compressão de anel à quente 200 °C. Assim como no ensaio de torneamento na velocidade de corte 220 m/min com o ensaio de compressão de anel à quente 400 °C. A análise macrográfica do anel após a deformação no ensaio de compressão de anel observou a influência da temperatura de ensaio no deslocamento do raio neutro. A análise superficial dos anéis e das matrizes do ensaio de compressão foi realizada por meio de microscopia óptica (MO) e rugosidade Ra, onde observou-se o aumento da rugosidade após o ensaio e a presença de desgaste abrasivo.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90926038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While excavation activities in mountain terrain regions, the exposure of carbonaceous mudstone could deteriorate the strength under the water-rock interaction, which impacts slope stability and affects the safety of the engineering project. The present study conducted the Point Loading Test (PLT), Acoustic Emission (AE)
{"title":"Study on time-effect to the strength deterioration of carbonaceous mudstone under water-rock interaction","authors":"Peng Mo, Qiongzhen Tang, Junhui Luo, Haifeng Huang, Qingping Yang, Yu Chen","doi":"10.1590/1517-7076-rmat-2023-0166","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0166","url":null,"abstract":"While excavation activities in mountain terrain regions, the exposure of carbonaceous mudstone could deteriorate the strength under the water-rock interaction, which impacts slope stability and affects the safety of the engineering project. The present study conducted the Point Loading Test (PLT), Acoustic Emission (AE)","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80456912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1590/1517-7076-rmat-2023-0178
Vinícius de Sousa Lima, Sandriel Lima Nascimento, Maria Luiza Rodrigues Gurgel da Silva, Marco Antonio Siviero, S. César, J. Molina, João Miguel Santos Dias
RESUMO O trabalho teve como objetivo determinar as propriedades físicas e mecânicas de painéis LVL de paricá (Schizolobium parahyba var. amazonicum (Huber x Ducke)) colados com resina ureia-formaldeído. Foram produzidos 6 painéis LVL com 17 lâminas de 2,5 mm de espessura, sendo 14 lâminas de paricá e 3 lâminas de marupá (Simarouba amara Aubl.). Para a condição de umidade padrão de 12%, foram realizados ensaios de teor de umidade, densidades aparente e básica (caracterização física), resistências à compressão paralela e perpendicular às fibras, tração paralela às fibras, cisalhamento na linha de cola e flexão estática flatwise e edgewise (caracterização mecânica). Na condição de saturação total da madeira, foram realizados ensaios de compressão paralela às fibras e cisalhamento na linha de cola do LVL. Os resultados mostraram que os painéis LVL se enquadram na classe de resistência D30, caracterizado com média densidade. Foi observado o modo de ruptura do tipo frágil em todos os ensaios mecânicos, exceto nos ensaios de compressão paralela e perpendicular às fibras. O aumento do teor de umidade, decorrente da saturação total da madeira, influenciou de forma negativa nas resistências à compressão paralela às fibras e ao cisalhamento na linha de cola. O LVL apresentou desempenho mecânico compatível com as solicitações estruturais.
摘要本研究旨在测定尿素甲醛树脂胶合parica (Schizolobium parahyba var. amazonicum (Huber x Ducke)) LVL板的物理力学性能。生产了6个LVL面板，17个2.5 mm厚的刀片，14个parica刀片和3个marupa刀片(Simarouba amara Aubl.)。在12%的标准湿度条件下，进行了含水率、表观密度和基本密度(物理特性)、平行和垂直于纤维的抗压强度、平行于纤维的拉伸强度、胶线剪切强度、平面和边缘静态弯曲强度(力学特性)等试验。在木材完全饱和条件下，进行了与纤维平行的压缩试验和LVL胶线的剪切试验。结果表明，LVL板的电阻等级为D30，密度为中等。除平行和垂直于纤维的压缩试验外，所有力学试验均观察到脆性断裂模式。由于木材的总饱和，水分含量的增加对纤维平行抗压强度和胶线剪切强度有负面影响。LVL的力学性能与结构要求一致。
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